#include <bits/stdc++.h>

using namespace std;

long long a, b, n;

int main()
{
    cin >> a >> b >> n;
    int ret = 0;
    int sum = a * 5 + b * 2;
    ret += 7 * (n / sum);
    n %= sum;
    for (int i = 1; i <= 5 && n > 0; ++i)
    {
        n -= a;
        ret++;
    }
    for (int i = 1; i <= 2 && n > 0; ++i)
    {
        n -= b;
        ret++;
    }
    cout << ret;
    return 0;
}